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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14118

Tidal water exchange drives fish and crustacean abundances in salt marshes

Paula de la Barra*, Martin W. Skov, Peter J. Lawrence, Juan I. Schiaffi, Jan G. Hiddink

*Corresponding author:

ABSTRACT: Coastal salt marshes provide an important habitat for fishes and crustaceans, including species of commercial value that feed or take refuge in the marsh. Yet, population abundances vary considerably between sites, often without clear explanation. We hypothesised that faunal abundance and mean size would be positively related to two physical properties that govern marsh accessibility to water dependent species, as has been found on the Southeastern coast of the USA: (1) the volume of water exchanged by tidal flooding, which gives access to the marsh, and (2) edge amount, the length of the water-vegetation borderline per unit area where species can take refuge and feed. Digital terrain models and tidal information were used to select five marshes in Wales, UK, that differed in edge amount and water exchange (52° N, 4° W). Fishes and crustaceans were sampled using baited traps, fyke nets and seine nets. Fifteen species were caught, including commercially valuable brown shrimp, European eel and sea bass. We found water exchange volume, but not edge amount, boosted fish and crustacean abundances. Crab and sea bass sizes were both negatively affected by water exchange, while shrimp and fish sizes were unaffected. Our findings show how the mechanisms that drive fish and crustacean abundances and sizes vary between geographical regions. Feasibly, fisheries associations with marsh hydrogeomorphology might operate differently in as well.